In continuous-motion packaging machines a carton which is not in the proper set-up condition for receiving articles to be packaged can hinder efficient operation of the machine. It would be useful to automatically determine when cartons would not be in proper condition to receive articles. It would also be useful to have a means for automatically ejecting a carton which is determined not to be in proper condition while preserving a synchronous relationship between a flow of cartons and a flow of articles to be packaged.